Twist blade switch



TWIST BLADE SWITCH 3 Sheets-Sheet 1 Filed June l, 1950 s w M M A w. E NvV L R A n. u .u l E H. H. M f M --@,L 1 -Lf L-: m w H Z s fa n t Ll T rLV@ i. M i R mm f M4 n n mv om 1 `Nm| QN MN m M. Vv/UIIIIIIIIIIH HH HHNH HlllllllllllhwllJ-Ik l .l u i m Q. wm vw @uw o w uw wv Qn, v w w a. Q.N\ G J Nm. Mm. lAI-IN S Jaw/www ATTORNEYS Sepi: 7, 1954 W, H G|| ANDETAL 2,688,666

TWIST BLADE SWITCH Filed June l, 1950 3 SheetsShee1l 2 lll/lill F/rzf/UGH H TURN/MM ATR 3R XEYS Sept 7, 1954 w. H. GILLILAND ETAL2,688,666

TWIST BLADE SWITCH 3 Sheets-Sheet 3 Filed June l, 1950 INVENTORS W/LL/AMH. G/LL/LA/vo l. 7 F rzHl/GH H TURN/MM f" BY JM, www

ATTORNEYS` of the blade.

`between the blade and jaw contacts. severe icing conditions arepresent, this added Patented Sept. 7, 1954 UNITED 4STATS PATENT .OFFICETWIST BLADE SWITCH William H. Gilliland and Fitzhugh H. Turnham,rBirmingham, Ala., assignors to USCO Power Equipment Corp., Birmingham,Ala., a. corporation of Alabama Application June 1, 1950, Serial No.165,546

(Cl. 20o- 48) 10 Claims.

This invention relates to high voltage switches ofv Ythe twist bladetype in which the switch blade .switches in the transmission of highamperage current.

In prior switchesv of this kind usedr to control higlrsamperagea itl hasbeen the practice to employ a heavy shunt-'at` the hinged end of theswitch to accommodate the very high amperage currents and a relativelyheavy, stiff, fixed jaw contact structure. 4As an alternativeconstruction, it hasalso been proposed to replace the heavy shunt with ajaw-type hinge contact assembly similar in construction to the contactassemblyV employed at the outer vorswinging end In eithercase,substantial resistance to yblade twist is-:developed necessitating lhigh applied: operating forces andvuneven pres-r surecontact often.results due to Vmisalignment Where resistance may be of sufficientmagnitude to prevent eiective yoperation -of the. switch.

Accordingly, 4it is ageneral object andpurpose .of vthe presentinvention toprovide novel blade contact assemblies comprising acylindrical or spherical contact at the hinge end of f the blade whichis at all times Aresiliently engaged with a mating stationary contactwhich offers a minifmum resistance to rotation of the blade and yetprovides ample contact area and mass for transmission of the heavycurrent in the desired manner and a self aligning jaw contact assemblyfor engagement by thev swing end oi the blade.

It is a' further object ofthe invention to provide a novel hinge contactassembly which assures positive contactr between the switch blade Iandthe hinge base at all times so vthat the contact has full capacity inall positions of the switch blade even during periods of extensivearcing in l opening and closing the switch.

It is a further object to provide a novel hinge contact assembly whichis simple in design, comprises a minimum number of structurally ruggedparts, and is inexpensive to manufacture and assemble.

In the conventional jaw-type stationary contact for the outer end-of`the switch blade, par- ..2 ticularlyV after a -period of use, accuratealignment. between the switch blade and the station- `ary contact oftencannot be maintained. This is particularly true where ythe' switch bladeis of :substantial length. -As a result-there may be considerablevariation in the pressure with which the blade engages theopposing jawsof the contact and consequently uneven wear von one contact surface. Inthe conventional jaw contact construction this situation can yberemedied only bymechanical bending of the jaws y or complete resetting-of the contact, neither of .which has proved to .becwholly satisfactoryin practice.

Accordingly, it is a further object toprovide anfmproved jaw-type outercontact assembly for aswitchv bladek switch which is self-aligning.

Itis a further object to providean improved outer contact assembly inwhich the4 engaging pressure may be easily .and accuratelywadjusted.

It isa further object toprovide an improved vcontact assemblyin whichthe-pressure of the opposing contact jawsis automatically maintained insubstantial equality.

Other objects and advantages will/,appear as the descriptionr proceeds-inconnection with the accompanying drawings in which:

Figure 1 is a sideelevation of a switch `illustrat- 4ingfone embodimentof the improvedwhinge contact construction of this invention;

Figure V2 is an enlarged sectional vView .taken along line 2-2 AofFigure 1;

contact assembly taken along line 4-4 of Figure- 1;

Figure 5 vis a side elevation partly inv section of a modifiedembodiment of the' hinge contact assembly of this invention;

Figure 6 is a fragmentaryy plan View taken along line 6 6 of Figure 5;

Figure 7 is a fragmentary side elevationfof still another hinge contactassemblyl embodying the presenty invention; and

"Figure 8 is a fragmentary plan View taken along line 8-8 of Figure' 7.

The present vinvention isconcerned only with contact assemblies. Thegeneral arrangement of the components ofthe switchV and the operatingmechanismv therefor are disclosed` and claimed in the copendingapplication of William H. Gilliland and Fitzhugh H. Turnham, Serial No.137,618,

rled January 9, i1950,fand entitled High Voltage Switch Assemblies.Therswitch is here described 3 only in so far as it is necessary for acomplete understanding of the construction and operation of the improvedhinge contact assembly.

Referring now to Figures 1-4 of the drawing, I indicates a base on whichare mounted a fixed insulator II vcarrying jaw-type contact I2 andarcing horns I3, a fixed insulator I4 supporting the hinge assembly I5,and a rotatable insulator I 6 carrying operating arm I1 at its lower endand operating linkage, indicated generally at I8, at its upper end. Asbest seen in Figure 4, extension I9 of switch blade 28, is formed intorectangular shape provided with a reinforcing insert, and is resilientlyand. frictionally clamped between op posed contacts I2. While anysuitable construction may be employed for contacts I2, the self aligningcontact of this invention to be hereinafter described is preferred.Blade 29 is journalled at its end opposite contacts I2 in sockets 22 and23 which are integral parts of bracket 24 (Figures 1 and 2) which ispivotally mounted on pin 25 for vertical rotation thereabout.

The mechanism for twisting and lifting switch blade 2l) includesoperating arm I1 and crank 25 mounted for co-movement on shaft 21 whichis journalled in bearings 28 and 29 respectively mounted in base Ii) anda conductor arm 30 interconnecting insulators I4 and I6. Pull rod 3| isconnected by universal joints 32 and 33 to crank 26 and rocker arm 34respectively. Legs 35 of rocker arm 34 are pivotally mounted on stubpins 36 mounted in ears 31 of fixed base 38. Lifting link 39 ispivotally mounted on pin 40 on bearing 22 and pivotally mounted at itsopposite end on pin 4I in rocker arm 34. Also pivotally mounted on pin4I is blade twisting link 42 which is connected through universal joint43 to the free end of crank arm 44 which is rigidly secured to switchblade 20.

The operation of the blade twisting and lifting mechanism thus fardescribed is as follows.

When operating arm I1 is rotated to open the switch, rocker arm 34together with pin 4I will be rotated in a counterclockwise directionabout pin 35. Since both lifting link 39 and twisting link 42 arepivotally secured to pin 4I at their upper ends and as their oppositeends are respectively disposed substantially radially inwardly of andsubstantially directly below pin 4I, link 39 will initially rotate aboutpin 49 without imparting any appreciable lifting movement to pin 40 orits supporting bracket 24 because of the substantial coincidence of thearcs of rotation of pin 4I around pins 36 and 40. Link 42 meanwhilesince it extends substantially directly downwardly from pin 4I willinitially be raised bodily upwardly due to the axial application offorce through pin 4I. As a consequence, the angular relationship oflinks 39 and 42 will be decreased while link 39 is maintained in tensionand link 42 imparts an upward force to universal joint 43. Sincedownward movement of pin 4I) is also prevented by the closed conditionof switch blade 20 and contacts I2, the force resulting from the foldingof links 39 and 42 is effective to rotate blade 20 in sockets 22 and 23twisting switch blade 28 through substantially 90 degrees to disrupt thefrictional bearing pressure of the blade contacts I2 and position theblade in a substantially vertical plane between the contacts. In thefurther upward swinging movement of the rocker arm the arcs of rotationof pin 4I around pins 36 and 40 separate imparting a lifting movement tolink 39. The angular relationship of the links at this time ismaintained and the bracket 24 with its journals 22 and 23 is swungupwardly through an arc of approximately degrees about the axis of pin25 to dispose the switch blade in the open position.

The above described operation is reversed when the switch is closed byrotation of the operating arm I1 in the opposite direction.

It will be apparent from the foregoing that the ease of operation of theswitch during initial twisting movement of the switch arm is dependentwholly upon the resistance to twist offered by the contacts at the innerand outer ends of switch blade 20. As aforementioned the presentinvention is concerned with minimizing the resistance to twist offeredby the inner or hinge contact without impairment of the effectiveness ofthe contact at this point.

Referring now to Figures 2 and 3, which illustrate a preferredembodiment of the improved hinged contact assembly, 41 indicates ahollow spherical stationary contact element rigidly attached to base 38by bolts 48. Pin 25, on which ears 5D of bracket 24 are mounted, passesthrough a diameter of contact 41, Bearings 22 and 23 carried in bracket24 are thus maintained in spaced relationship to contact 41'and arerotatable about the axis of pin 25. A female contact 5I is disposedwithin the hollow `journalled end of blade 29 and rigidly securedthereto as by pin 52. A press t is preferably maintained between contact5I and blade 20 to assure positive contact between the members over alarge surface. A spherical recess 53 having a radius equal to that ofthe outer surface of contact 41 is provided in an enlarged portion 54 ofcontact 5I protruding beyond the end of blade 20. To assure positiveengagement of the mating surfaces of contacts 41 and 5I, a spring 55 iscompressed between shoulder 56 of contact 5I and bearing 22,` bearings22 and 23 being spaced sufficiently to allow axial movement of link 44therebetween and axial movement of blade 29 and contact 5I intoengagement with contact 41. This hinge contact assembly is especiallyadvantageous in that it minimizes the resistance to rotation of theswitch blade 20 and assures positive contact over a large area at alltimes regardless of the position of switch blade 20 and contacts I2.Accordingly, even though arcing occurs between blade 20 and contacts I2during opening and closing movement of the switch, full electricalcontact is always maintained at the hinged end of the switch.

Referring now to Figures 5 and 6, which illustrate an alternative hingecontact construction, a spherical male contact member 51 forms anextension of a stem 58 which is received within the hollow end of switchblade 20 and rigidly attached thereto as by pin 59. To facilitateassembly, contact 51 is purposely made small enough so that it may bepassed through bearings 22 and 23 after being assembled on blade 28.Stem 58 and blade 20 preferably have a press fit to assure full andtight surface engagement between them. Contact 51 is frictionallyreceived in spherical recesses 6D formed in a pair of opposing contacts6I disposed between ears 50 and rigidly mounted on base'38 as by bolts62. The frictional engagement between Contact 51 and contacts 6I isadjustably maintained by a pair of spring washers 63 which are held inresilient engagement with the outer surface of contacts 5I as by bolts64. Nut 65 and lock nut 66 are provided to adjust the engaging pressurebetween contacts 6I and contact 51.

Figures 7 and 8v illustrate a: third embodiment of the hinge contactVconstruction which is similar in all respects to the embodimentofiFigures'B and 6 described aboveV except that. switch blade 20 isextended so as tobe received between apair of opposing contactsformedfby U-shaped member 61 and thus forms one oil the contactelements. Spring washers 63, bolt 64 and nuts 65 and 66 similar to thosedescribed in connection with Figure 7 are provided to maintainanadjustable frictional engagement-between the contacts. The arcuatesection 6B at the lower ends of contacts 61 is preferably held in anarcuate seat 68' formed on base 38 by clamping members 69 and bolts 1Ithreaded into seat t8 of base 38.

Referring again to Figure 4, each of the two pairs of contact jaws I2 ispreferably formed from a single relatively flexible. piece of metal bentinto U-shape and having outwardly flaring portions at its upper end. Thebridge section 12 of each pair of jaws I2 is clamped between a lower'clamping member 13, which is rigidly attached to insulator II, and anupper clamping member 14, as by bolts 14. Clamp 13 is provided with acentrally located upwardly extending ear 15, which is apertured toreceive a loosely iitting ypin 16. Mounted on pin 1G are spaced lugs 11attached to the lower edge of a plate 18. which is received between thelongitudinally spaced pairs ofcontact jaws I2, as shown in Figure l. Apair of opposing spring housings 'i9 form an integral part of plate 18and are positioned outwardly of both pairs of contacts I2v (Figure l).'A spring 2l disposed in each housing 19 is compressed between a bearingplatet which engages the respective two adjacent contacts i2, andbearing plate 8| received within housing 19. An adjusting screw 82 andlock nut 83 are provided to regulate the respective compression springs2|. A pair of stops 84' are provided on plate 18 to limit the inwardmovement of contacts I2.

In operation, assuming for example that the switch blade 2li' isslightly out of alignmentA to the left, the engaging pressure on theleft side of extension Ie will initiallybe greater than. that on theright side. This will result in a slight displacement of the leftcontact jaws i 2 to the left, increasing the compression of the leftspring 2l. Since plate 13 is free to pivot about pin 16, it will berotated slightly in a counter-clockwise direction until the compressionof the opposing spring 2| is substantially equal. Thus, the entirecontact assembly will tend to come into automatic alignment with theswitch blade 2Q.

It will be understood that the degree to which the contact jaws are self-aligning depends in large measure on the flexibility of the contactshoes. If, as in the prior art, the jaws are made suiiciently rigid tofurnish the entire contact pressure between the jaws and the bladecontact, the contact jaws or shoes will absorb the excessive contactpressure due to misalignment of the blade and impose a high resistanceto movement of the blade to fully closed or opened position. Thisinvention, therefore, contemplates the use of relatively light, flexiblejaws or shoes and self compensating opposed pressure springs 2| whichare brought into play in event of misalignment to permit relatively freeand successive lateral movement of the jaws in the same direction to aposition in substantial alignment with the blade. On the other hand, theshoes must possess sufficient rigidity to prevent deformation beyondtheir elastic limit. In practice, the jaws or shoes may have any degreeof ilexibility above that necessaryl .to avoidy permanent deformationbut less than that which will-prevent relatively freelateralSdisplacement-by theblade moving to closed position, theoptimumflexibility being determined in individual cases` with regard tothe f size of theswitch, the twist bladaami' the amount' of use required.in service.

It is also to. be noted that in the'completely closedposition of theblade 20, shown in Figure 4, extension I9 is oenteredwith respect tospring 2 I. Consequently, thecontact pressure is exerted directlythrough the center line of thexcxtension, thereby assuring uniformityofthe contact pressure and minimizing thei objectionablefeffects ofbending or Wear of .the contact jaws I2.

'It is feltr that ytheoperation of the various hinge contact assemblieswill be obvious from the foregoing description.

It is to be noted that in each construction the hinged contacts .areinresilient engagement at all times, that the areaof contact isA constantin all positions of .the-'switch armthat the contacts are self cleaningbecause of the rotation about two axes in each operation of the switch,and thatA in eachof the constructions the frictional resistance to.twisting and swinging Vmovementiof the switch arm is minimized.

The invention` may `be embodied in other speciiic forms withoutdepartment from the spirit-or essential characteristics thereof, thepresent ernbodiments are therefore -to bey considered in all respects asillustrative `and Lnot restrictive, the scope of vthe invention beingindicated bythe appendedv claims ratherV than 'by'L the foregoingdescriptionl and.` all changes which come within the meaning and rangeYof equivalency of the claims are therefore 'intended to be embracedtherein.

What is claimed and desired to be secured vby United States. Patent is:

1.. An electric transmission line switch comprising a'pair'of spaced,xed supporting insulators; a fixed bifurcated contact mounted on lone ofsaid .fixed insulators; a twistb-lade switch pivotally and rotatablymounted on said other insulator and adaptedtobe rotated about itslongitudinalaxis to establish firm contactwithsaid xed bifurcatedcontact and to swingaround its pivotal` axis into and out' ofv contactwith' said fixed bifurcated contact; a second stationary contact mountedon said-other insulator and having a contact portion in transverselyaligned relation to the pivotal axis of said switch blade; and contactmeans on said switch blade of circular cross-sectionI in a plane normalto the axisy of said switch blade rotatably and pivotally movabletherewith and comprising an elongated portion extending into the pivotedend of said switch and having an enlarged contact end protruding axiallyof said switch blade into cooperating engagement with said contactportion of said second stationary contact and adapted to establishcontact therewith in full contacting capacity and constant contact areain all positions of said switch blade. j

2. The combination defined in claim 1 wherein said switch blade ismounted for limited axial movement in a pair of axially spaced journalsockets and a compression spring is mounted in encircling relation tothe end of said switch blade with its opposite ends respectivelyengaging said enlarged contact end and the adjacent one of said spacedjournal sockets to resiliently urge said switch blade and its attachedcontact means axially into rm engagement with said second contactstationary contact.

3. A hinge contact assembly for a twist blade switch comprising a bladecontact having an elongated portion extending into the pivotal end ofsaid switch blade and an enlarged contact end protruding axially fromswitch blade end and providing a spherical contact area coincident withthe longitudinal axis of said switch blade; and a stationary terminalcontact element adapted to continuously engage said blade contact andhaving a reversely mating spherical contact area the center of which iscoincident with the pivotal axis of said switch blade and the1ongitudinal axis of said switch blade whereby, upon pivotal andtwisting movement of said blade, said mating contact areas aremaintained in full sulface contacting capacity and constant Contactarea.

4. The combination defined in claim 3 together with means to resilientlyurge said contacts into firm mating engagement to assure good electricalcontact and a self-cleaning rubbing contact between said contactingareas.

5. The combination defined in claim 4 wherein said means for resilientlyurging said contacts into engagement comprises a compression springadapted to urge said switch blade and said blade contact axially intoengagement with said stationary contact.

6. The combination defined in claim 4 wherein said stationary contactcomprises a pair of laterally spaced arms having oppositely inwardlyfacing depressions and spring means is provided comprising atransversely extending headed bolt member extending freely through saidspaced arms, a pair of dished spring washers respectively disposed incontact with said head and on its opposite end, and a nut threadedlyassociated with said opposite end and adapted to be threaded thereon totension said spring washers to resiliently urge said arms inwardly intocontact with said blade contact.

7. The combination defined in claim 4 wherein said static-nary contactcomprises a ball shaped member and said resilient means comprises acompression spring disposed in encircling relation to said switch bladeend with one end in contact with said enlarged contact end so as to urgesaid blade contact axially into engagement with said ball shaped member.

8. In an electrical twist blade switch having a hinge end contactassembly: a swing end jaw contact assembly for receiving the swing endof said blade comprising highly flexible laterally spaced jaws and meansassociated with said spaced jaws to automatically shift said respectivejaw contacts to properly receive the swing end of said blade andthereafter maintain uniform pressure engagement between each of saidjaws and said blade in the closed position of said switch whereby propercontact is assured in spite of slight misalignment of said twist bladeand said contact assemblies and the number of opening and closingmovements of said switch.

9. 1n an electric twist blade switch: a bifurcated relatively stationaryswing end contact; a blade contact movable into and out of engagementwith said stationary contact; and means to automatically shift saidrelatively stationary contact with respect to said blade contact toassure substantially equal pressure contact between said blade contactand the arms of said bifurcated contact when said blade is moved intoengagement with said stationary contact.

10. In an electric twist blade switch: a swing end contact assemblycomprising a blade contact, a pair of opposed jaw contacts adapted toengage opposite sides of said blade contact; respective resilient meansadapted to control the engaging pressure between said blade contact andeach of said opposed jaw contacts; and means responsive to engagement ofsaid blade contact with said opposed jaw contacts to vary the pressureexerted by one of the said pair of resilient means in response to avariation in the pressure exerted by the other of said pair of resilientmeans.

References Cited in the le of this patent UNITED STATES PATENTS NumberName Date 1,560,165 Johnson Nov. 3, 1925 1,831,843 Corni-leid Nov.17,1931 2,363,307 Florschutz Nov. 2l, 1944 2,453,011 Graybill Nov. 2,1948 2,531,165 Scheurmeyer Nov. 21,1950 2,545,940 Caldwell Mar. 20, 1951

